Method and Apparatus for Wetting Internal Fluid Path Surfaces of a Fluid Port to Increase Ultrasonic Signal Transmission

ABSTRACT

A method for readying a fluid sensor associated with a medical device includes attaching a flow restrictor to a fluid outlet of the fluid sensor. The fluid sensor includes a fluid channel, a fluid inlet at a first end of the fluid channel configured to couple to an outlet of an administrable fluid source, and the fluid outlet at a second end of the fluid channel. Fluid is delivered from the administrable fluid source to the fluid channel through the fluid inlet. A syringe actuation device including a force limiting device may be used to deliver the fluid. The fluid is pressurized in the fluid channel between the fluid inlet and the flow restrictor to wet an interior surface of the fluid channel with the fluid. The flow restrictor is removed from the fluid outlet.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 16/293,929 filed Mar. 6, 2019, which is a continuation of U.S.patent application Ser. No. 15/626,510 filed Jun. 19, 2017 (now U.S.Pat. No. 10,258,742), which claims priority to U.S. Provisional PatentApplication No. 62/351,459 filed Jun. 17, 2016, the entire disclosuresof which are herein incorporated by reference.

BACKGROUND OF THE INVENTION 1. Field of the Disclosure

The present disclosure relates generally to a flow sensor system. Moreparticularly, the present disclosure relates to a flow sensor system anda method of readying a flow sensor of the flow sensor system forcharacterizing at least one attribute of a fluid to be detected by theflow sensor.

2. Description of the Related Art

There is a need to improve volume accuracy in a bolus delivery using amedical device. It would be advantageous to provide a flow sensor systemhaving a flow sensor with improved flow measurement characteristics.

Signal strength is a function of acoustic energy propagation from asource through a boundary layer of air (and/or contaminants) thatattenuate this propagation. As a sensor is first subjected to a fluid, aboundary is initially formed. Over time this layer begins to break downleaving micro-bubbles of air at the surface of the sensor. Micro-bubblesremain at the surface as a function of two theories: i) the partialpressure of air dissolved in the fluid and ii) the surface energy orcapillary forces of a micro-bubble with respect to the surface. Lowerpressure fluids contain a smaller partial pressure of air and may permitthe absorption of air into the fluid. Higher pressure applied to thefluid can both shrink the bubbles and permit more surface area incontact with the fluid and, upon release, permit a detachment of themicro-bubbles to absorb into the fluid. Based on the surface topology orasperity density, micro-bubbles become lodged into cavities of thesurface by capillary action or surface tension that is higher thanfloating in the fluid itself.

Accordingly, there is a need in the art for an improved method andapparatus for wetting internal fluid path surfaces of a fluid port toincrease ultrasonic signal transmission.

SUMMARY OF THE INVENTION

The present disclosure provides a system for sensing a flow of a fluidicmedicament. The system includes an intelligent injection port which mayattach to an injection site (such as a “Y Site” or a stop cock) formanually administered IV injections. The system includes two mainsub-assemblies: a single-use flow sensor and a reusable base unit, whichfit together prior to use. The single-use flow sensor includes a flowtube sub-assembly. The present disclosure provides a method for readyingthe flow sensor for characterizing at least one attribute of the fluidflowing through the flow tube sub-assembly.

According to a non-limiting embodiment or aspect, provided is a methodfor readying a fluid sensor associated with a medical device, the methodcomprising: attaching a flow restrictor to a fluid outlet of the fluidsensor, the fluid sensor comprising: a fluid channel, a fluid inlet at afirst end of the fluid channel configured to couple to an outlet of anadministrable fluid source, and the fluid outlet at a second end of thefluid channel; delivering fluid from the administrable fluid source tothe fluid channel through the fluid inlet; pressurizing the fluid in thefluid channel between the fluid inlet and the flow restrictor to wet aninterior surface of the fluid channel with the fluid; and removing theflow restrictor from the fluid outlet.

In one non-limiting embodiment or aspect, the method further comprisesapplying a pressure to the fluid in the fluid channel between the fluidinlet and the flow restrictor over a first period of time.

In one non-limiting embodiment or aspect, the administrable fluid sourcecomprises a syringe including a plunger, wherein the method furthercomprises: attaching a syringe actuation device to the syringe; andapplying, with the syringe actuation device, a force to the plunger ofthe syringe.

In one non-limiting embodiment or aspect, the method further comprisesadjusting the syringe actuation device to a first position, wherein,when in the first position, the syringe actuation device applies theforce to the plunger of the syringe.

In one non-limiting embodiment or aspect, the pressure is a constantpositive pressure.

In one non-limiting embodiment or aspect, the pressure is a constantnegative pressure.

In one non-limiting embodiment or aspect, the method further comprisesapplying a constant pressure to the fluid in the fluid channel betweenthe fluid inlet and the flow restrictor over a second period of timethat is one of before the first period of time and after the firstperiod of time.

In one non-limiting embodiment or aspect, the administrable fluid sourcecomprises a syringe including a plunger, the method further comprising:attaching a syringe actuation device to the syringe; adjusting thesyringe actuation device to a first position, wherein, when in the firstposition, the syringe actuation device applies a first constant force tothe plunger of the syringe that applies the constant negative pressureto the fluid in the fluid channel over the first period of time; andadjusting the syringe actuation device to a second position, wherein,when in the second position, the syringe actuation device applies asecond constant force to the plunger of the syringe that applies theconstant positive pressure to the fluid in the fluid channel over thesecond period of time.

In one non-limiting embodiment or aspect, the method further comprisescreating a bi-directional flow of the fluid in the fluid channel betweenthe fluid inlet and the flow restrictor.

In one non-limiting embodiment or aspect, the method further comprisesapplying a varying pressure to the fluid in the fluid channel betweenthe fluid inlet and the flow restrictor.

In one non-limiting embodiment or aspect, the flow restrictor comprisesan outlet having an inner diameter that changes in response to thevarying pressure applied to the fluid in the fluid channel, therebycreating a perturbative flow of the fluid in the fluid channel.

In one non-limiting embodiment or aspect, the flow restrictor comprisesan elastomeric material.

In one non-limiting embodiment or aspect, the administrable fluid sourcecomprises a syringe having a plunger, wherein the method furthercomprises: mounting the syringe vertically in a syringe holder; andapplying a load to the plunger of the syringe.

In one non-limiting embodiment or aspect, the method further comprisesshaking or vibrating the fluid sensor when the fluid is within the fluidchannel.

In one non-limiting embodiment or aspect, the fluid sensor furthercomprises at least one piezo element, wherein the method furthercomprises: activating the at least one piezo element when the fluid iswithin the fluid channel, thereby dislodging micro-bubbles from innerwalls of the fluid channel.

In one non-limiting embodiment or aspect, the method further compriseswetting the fluid channel with at least one surfactant.

In one non-limiting embodiment or aspect, the method further comprisesprocessing at least one component of the fluid sensor using at least oneof plasma etching, abrasive polishing, reaming, or any combinationthereof to reduce surface roughness of the at least one component.

In one non-limiting embodiment or aspect, the method further comprisesapplying a negative pressure to the fluid in the administrable fluidsource before delivering the fluid from the administrable fluid sourceto the fluid channel through the fluid inlet, thereby removing gas fromthe fluid.

In one non-limiting embodiment or aspect, the method further comprisesattaching a suction cup to the fluid inlet; and actuating the suctioncup to apply the negative pressure to the fluid in the administrablefluid source.

In one non-limiting embodiment or aspect, the method further comprisesattaching a flow director between the fluid inlet at the first end ofthe fluid channel and the outlet of the administrable fluid source,wherein the flow director creates a spiral fluid flow in the fluiddelivered from the administrable fluid source to the fluid channelthrough the fluid inlet.

In one non-limiting embodiment or aspect, the method further comprisesheating the fluid when the fluid is within the fluid channel.

In one non-limiting embodiment or aspect, the method further comprisesvarying a flow rate of the fluid delivered from the administrable fluidsource to the fluid channel through the fluid inlet.

In one non-limiting embodiment or aspect, the delivering the fluid fromthe administrable fluid source to the fluid channel through the fluidinlet comprises delivering boluses of the fluid from the administrablefluid source to the fluid channel through the fluid inlet.

In one non-limiting embodiment or aspect, the boluses are periodicallydelivered to the fluid channel.

In one non-limiting embodiment or aspect, the method further comprisesvarying at least one of the following: a volume of the boluses, apressure applied to the fluid of the boluses, a period of time overwhich the pressure is applied to the fluid of the boluses, or anycombination thereof.

In one non-limiting embodiment or aspect, the administrable fluid sourcecomprises a syringe including a plunger, and wherein the method furthercomprises: attaching a force limiting device to the syringe; andinhibiting, with the force limiting device, an application of a pressureto the fluid in the fluid channel that violates a threshold pressure.

In one non-limiting embodiment or aspect, the force limiting deviceinhibits movement of the plunger of the syringe in response to theapplication of the pressure to the fluid in the fluid channel thatviolates the pressure threshold.

In one non-limiting embodiment or aspect, the administrable fluid sourcecomprises a syringe including a plunger, and wherein the method furthercomprises: attaching a force limiting device to the syringe, the forcelimiting device including at least one pressure indicator; andindicating, with the at least pressure indicator, a current pressureapplied to the fluid in the fluid channel.

In one non-limiting embodiment or aspect, said flow restrictor furthercomprises an outlet of approximately 34 G (0.0826 mm ID).

According to a non-limiting embodiment or aspect, provided is a methodfor readying a fluidic conduit associated with a medical device, themethod comprising: attaching a flow restrictor to a fluid outlet of thefluidic conduit, the fluid conduit comprising: a fluid channel, a fluidinlet at a first end of the fluid channel configured to couple to anoutlet of an administrable fluid source, and the fluid outlet at asecond end of the fluid channel; delivering fluid from the administrablefluid source to the fluid channel through the fluid inlet; pressurizingthe fluid in the fluid channel between the fluid inlet and the flowrestrictor to wet an interior surface of the fluid channel with thefluid, thereby removing air bubbles from the pressurized fluid in thefluidic conduit; and removing the flow restrictor from the fluid outlet.

According to a non-limiting embodiment or aspect, provided is a methodfor readying a fluid sensor associated with a medical device comprising:generating a first signal by at least one sensor of a fluid portcharacterizing at least one attribute of a fluid within an administrablefluid source, the fluid port comprising: a fluid channel, a fluid inletat a first end of the fluid channel configured to couple to an outlet ofan administrable fluid source, and a fluid outlet at a second end of thefluid channel having a flow restrictor; removing the flow restrictor;attaching the fluid outlet at a second end of the fluid channel to aninlet configured to deliver fluid from the administrable fluid source toa fluid pathway that provides fluid to said medical device; generating asecond signal of the same type as said first signal by at least onesensor of a fluid port characterizing at least one attribute of fluid,wherein said second signal is increased over the first signal.

According to a non-limiting embodiment or aspect, provided is anapparatus for controlling a plunger of a syringe to deliver a fluid froman interior of the syringe, comprising: an actuator rod extending from aproximal end to a distal end; a plunger engagement portion engaged withthe distal end of the actuator rod and configured to engage the plungerof the syringe; a body having a proximal end, a distal end, and anopening at the proximal end, wherein the opening receives the plungerengagement portion, and wherein the plunger engagement portion isthreadably engaged with the body.

In one non-limiting embodiment or aspect, the plunger engagement portionis configured to inhibit an application of a force to the plunger of thesyringe that violates a threshold force.

In one non-limiting embodiment or aspect, the plunger engagement portioninhibits movement of the plunger of the syringe in response to a plungerreaction force applied by the plunger of the syringe.

In one non-limiting embodiment or aspect, the apparatus furthercomprises a clutch that engages the distal end of the actuator rod tothe plunger engagement portion.

In one non-limiting embodiment or aspect, the apparatus furthercomprises a spring that extends within the actuator rod.

In one non-limiting embodiment or aspect, the spring extends within theactuator rod and into the plunger engagement portion via an opening in aproximal end of the plunger engagement portion, and wherein the springengages an inner wall at the distal end of the plunger engagementportion.

In one non-limiting embodiment or aspect, an outer wall at the distalend of the plunger engagement portion engages the plunger.

In one non-limiting embodiment or aspect, the actuator rod extends intothe plunger engagement portion, wherein a portion of the actuator rodthat extends within the plunger engagement portion includes a radiallyextending flange, and wherein the clutch connects a proximal face of theflange to the inner wall at the proximal end of the plunger engagementportion.

In one non-limiting embodiment or aspect, the clutch disengages thedistal end of the actuator rod from the plunger engagement section inresponse to a compression of the spring.

In one non-limiting embodiment or aspect, the spring compresses inresponse to a plunger reaction force applied by the plunger of thesyringe to the plunger engagement portion.

In one non-limiting embodiment or aspect, the distal end of the body isconfigured to connect to the syringe, and wherein the plunger of thesyringe extends within the body.

According to a non-limiting embodiment or aspect, provided is anapparatus for controlling a plunger of a syringe for delivering a fluidfrom an interior of the syringe, the device comprising: a handle and acooperating trigger, wherein the trigger comprises a first portionconnected to a second portion by a joint; and a spring connecting thefirst portion to the second portion; wherein the first portion of thetrigger is configured to engage the plunger of the syringe and receive aplunger reaction force applied by the plunger of the syringe, whereinmovement of the second portion of the trigger toward the handle appliesa stretching force to the spring in response to the plunger reactionforce, and wherein the first portion of the trigger disengages theplunger of the syringe in response to the stretching force greater thana threshold force applied to the spring.

In one non-limiting embodiment or aspect, the handle and the cooperatingtrigger operate one of a spring biased grip drive and a ratchet drivengrip drive.

In one non-limiting embodiment or aspect, the first portion of thetrigger engages the plunger of the syringe via at least one of a pistonand a drive grip, and wherein the first portion of the trigger breaksthe engagement with the at least one of the piston and the drive grip inresponse to the stretching force greater than the threshold forceapplied to the spring.

According to a non-limiting embodiment or aspect, provided is anapparatus for controlling a plunger of a syringe for delivering a fluidfrom an interior of the syringe, the device comprising: an actuator rodextending from a proximal end to a distal end; a spring extending withinthe actuator rod, wherein a distal end of the spring is configured toengage the plunger of the syringe; a body having a proximal end, adistal end, and an opening at the proximal end, wherein the openingreceives the distal end of the actuator rod, and wherein the actuatorrod comprises at least one indicator that indicates a desired amount ofcompression of the spring.

In one non-limiting embodiment or aspect, an outer wall of the actuatorrod is in ratcheting engagement with an inner wall of the body.

In one non-limiting embodiment or aspect, a distal end of the actuatorrod comprises a radially extending pawl, and wherein the inner wall ofthe body comprises a plurality of teeth.

In one non-limiting embodiment or aspect, at least a portion of theactuator rod and at least a portion of the body are transparent suchthat the spring and the plunger are visible through the actuator rod andthe body.

In one non-limiting embodiment or aspect, a location of the at least oneindicator with respect to a location of at least one of a distal end ofthe spring and a proximal end of the plunger indicates the desiredamount of compression of the spring.

In one non-limiting embodiment or aspect, the actuator rod comprises atleast two indicators spaced apart from one another, and wherein alocation of the at least one of the distal end of the spring and theproximal end of the plunger between the at least two indicatorsindicates the desired amount of compression of the spring.

In one non-limiting embodiment or aspect, the distal end of the body isconfigured to connect to the syringe, wherein the plunger of the syringeextends within the body.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of thisdisclosure, and the manner of attaining them, will become more apparentand the disclosure itself will be better understood by reference to thefollowing descriptions of examples of the disclosure taken inconjunction with the accompanying drawings, wherein:

FIG. 1 is a distally-directed perspective view of a flow sensor systemin accordance with one example of the present invention.

FIG. 2 is a distally-directed perspective view of a flow sensor systemin accordance with one example of the present invention.

FIG. 3 is an exploded, perspective view of a flow sensor of a flowsensor system in accordance with an example of the present invention.

FIG. 4 is a perspective view of a flow sensor of a flow sensor system inaccordance with an example of the present invention.

FIG. 5 is a graph showing signal level of a flow sensor of a flow sensorsystem as a function of time according to one example case.

FIG. 6 is a graph showing signal level of a flow sensor of a flow sensorsystem as a function of time according to another example case.

FIG. 7 illustrates a holder for a syringe in a flow sensor system inaccordance with an example of the present invention.

FIG. 8 illustrates an exemplary configuration of a force limiting deviceof a flow sensor system in accordance with an example of the presentinvention.

FIG. 9 illustrates an exemplary configuration of a force limiting deviceof a flow sensor system in accordance with an example of the presentinvention.

FIG. 10 illustrates an exemplary configuration of a force limitingdevice of a flow sensor system in accordance with an example of thepresent invention.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate exemplary examples of the disclosure, and suchexemplifications are not to be construed as limiting the scope of thedisclosure in any manner.

DETAILED DESCRIPTION

The following description is provided to enable those skilled in the artto make and use the described examples contemplated for carrying out theinvention. Various modifications, equivalents, variations, andalternatives, however, will remain readily apparent to those skilled inthe art. Any and all such modifications, variations, equivalents, andalternatives are intended to fall within the spirit and scope of thepresent invention.

For purposes of the description hereinafter, the terms “upper”, “lower”,“right”, “left”, “vertical”, “horizontal”, “top”, “bottom”, “lateral”,“longitudinal”, and derivatives thereof shall relate to the invention asit is oriented in the drawing figures. However, it is to be understoodthat the invention may assume various alternative variations, exceptwhere expressly specified to the contrary.

As used in the specification and the claims, the singular form of “a”,“an”, and “the” include plural referents unless the context clearlydictates otherwise.

As used herein, “proximal” shall refer to a part or direction locatedaway or furthest from a patient (upstream), while distal shall refer toa part or direction towards or located nearest to a patient(downstream). Also, a drug substance is used herein in an illustrative,non-limiting manner to refer to any substance injectable into the bodyof a patient for any purpose. Reference to a patient may be to anybeing, human or animal. Reference to a clinician may be to any person orthing giving treatment, e.g., a nurse, doctor, machine intelligence,caregiver, or even self-treatment.

As used herein, the phrase “inherently hydrophobic” refers to a surfacethat naturally excludes water molecules rather than by a process ofdrying, such as drying by hot air.

Unless otherwise indicated, all ranges or ratios disclosed herein are tobe understood to encompass any and all subranges or subratios subsumedtherein. For example, a stated range or ratio of “1 to 10” should beconsidered to include any and all subranges between (and inclusive of)the minimum value of 1 and the maximum value of 10; that is, allsubranges or subratios beginning with a minimum value of 1 or more andending with a maximum value of 10 or less, such as but not limited to, 1to 6.1, 3.5 to 7.8, and 5.5 to 10.

Unless otherwise indicated, all numbers expressing quantities used inthe specification and/or claims are to be understood as modified in allinstances by the term “about.”

Flow Sensor System

FIGS. 1-4 illustrate an exemplary configuration of a flow sensor system200 of the present disclosure. Referring to FIGS. 1-4, a flow sensorsystem 200 of the present disclosure includes two main assemblies whichfit together prior to use: a flow sensor 210 and a base 220. In oneexample, the flow sensor 210 can be a single-use flow sensor which isengageable with a reusable base 220. The flow sensor system 200 is anintelligent injection port. The flow sensor system 200 is attachable toan injection site (“Y Site” or stop cock, for example) for manuallyadministered IV injections.

The flow sensor system 200 of the present disclosure can reducemedication error at bedside during bolus delivery. The flow sensorsystem 200 of the present disclosure can also provide a record of andelectronically measure bolus delivery, which allows monitoring bolusdelivery and automatic documentation of bolus delivery as part of apatient's health record. The flow sensor system 200 of the presentdisclosure can also provide alerts when bolus delivery inconsistent witha patient's medical record is about to occur.

Referring to FIGS. 1-4, in one example, the base 220 is a non-sterile,reusable device that houses a battery, a scanner (either optical,mechanical, inductive, capacitive, proximity, or RFID), electronics, anda wireless transmitter. In some examples, the base 220 is batterypowered and rechargeable. In some examples, each base 220 has a uniqueserial number imprinted on a surface of the base 220 or embedded thereinthat may be transmitted to a data system before use. The data system canbe a local computer or tablet “computer”, a cellular phone, anothermedical device, or a Hospital Data System.

Referring to FIGS. 1-4, in one example, the base 220 is removablyconnectable to the flow sensor 210 and includes at least one deflectablewing tab 280 defining an opening for receiving at least a portion of theflow sensor 210 therein and for securing the flow sensor 210 within aportion of the base 220 prior to use. In one example, a pair of wingtabs 280 secure the flow sensor 210 within the base 220. The wing tabs280 may be flexible to the extent that they may be outwardly deflectedto allow for passage of the flow sensor 210 thereover. In one example,the flow sensor 210 is a pre-sterilized disposable device having aninjection port 130 and a distal tubing connection, such as a Luer tip109, which may be optionally covered by a Luer cap 108.

With reference to FIG. 3, the flow sensor 210 may include a flow tubesub-assembly 10 consisting of a flow tube 100 having an outlet end 101and an inlet end 102. The outlet end 101 may be provided in fluidcommunication with an outlet tubing 110 having an outlet connection 105including a Luer tip 109 which may be optionally covered by a flowrestrictor, as described herein. In a preferred example, the outletconnection 105 is a plastic connector with a Luer tip 109, however, anysuitable method to inject the medicament into a patient is envisaged tobe within an aspect of an example of the invention. For example, it maybe desirable to replace the outlet connection 105 and tubing 110 with aneedle for direct injection/infusion into a patient. In some examples,components of the flow tube sub-assembly 10, such as the flow tube 100and sensor fittings, can be pre-processed or post-processed using plasmaetching, abrasive polishing, and/or reaming to reduce surface roughnessof the components of the flow tube sub-assembly 10, which can reduce theformation of micro-bubbles at the inner walls of flow tube 100.

The inlet end 102 may be coupled to the reservoir of a medication pen orinfusion reservoir. The inlet end 102 of the flow tube 100 may beprovided in fluid communication with an injection port 130, and mayoptionally include a connection such as a threaded Luer lock 131 whichis engageable with a source of a fluid to be injected. A pierceableseptum (not shown) may be provided with the injection port 130 formaintaining sterility prior to use. In one example, the flow tube 100 iscomprised of a medical grade stainless steel and is approximately 50 mmlong with a 1.0 mm inner diameter and a 1.6 mm outer diameter.

In one example, the flow sensor system 200 supports injections using anyLuer-lock type syringe or liquid medicament container. Additionally, theflow sensor system 200 is designed to work with encoded syringes thathave a special barcode identifier on the Luer collar of the syringe,called “encoding”. Preferably, encoded syringes includecommercially-available drugs in prefilled syringes with a specialbarcode that stores information about the medication contained withinthe syringe. Encoded syringes are ready-to-use, passive, and disposable.The encoding syringes store the drug name and concentration containedwithin the syringe. Additional characteristics such as drug source,container size, drug manufacturer source, drug category color, amongothers, may also be included. When an encoded syringe is attached to theinjection port 130 of the flow sensor 210, this barcode information isread by a scanner in the base 220 and wirelessly transmitted by the flowsensor system 200 to the data system. Preferably, the 2-D barcodes willbe added to syringes during the filling process. The flow sensor system200 also accommodates syringes not having encoding.

The present disclosure provides a flow sensor sub-assembly for sensingflow of a fluidic medicament. The flow sensor 210 also includes a firstpiezo element or an upstream transducer 150 and a second piezo elementor a downstream transducer 151. The first piezo element 150 may beprovided with an inlet fitting 180, as shown in FIG. 3, for couplingwith the injection port 130. Similarly, the second piezo element 151 maybe provided with an outlet fitting 190, for coupling with the outlettubing 110. The first and second piezo elements 150 and 151 areconfigured to transmit an ultrasonic signal therebetween indicative of aflow of the fluidic medicament in the flow tube 100. In an example, thefirst piezo element 150 and the second piezo element 151 are annular inshape and encircle the flow tube 100 at each respective mounting point.In some examples, the flow sensor 210 may comprise a measuringinstrument as disclosed in U.S. Pat. No. 7,255,006, which is herebyincorporated by reference in its entirety, to measure a flow of thefluidic medicament in the flow tube 100.

The flow sensor 210 includes a first spring contact 750 a and a secondspring contact 750 b. In one example, the spring contacts 750 a, 750 bare secured to a base 700 that has a circuit for conducting anelectrical signal to and from the spring contacts 750 a, 750 b to amicroprocessor. The first spring contact 750 a is in electricalcommunication with a first piezo element 150 and the second springcontact 750 b is in electrical communication with a second piezo element151. The first spring contact 750 a has a first contact force againstthe first piezo element 150 and the second spring contact 750 b has asecond contact force against the second piezo element 151. The firstcontact force may be equivalent to the second contact force. The firstand second piezo elements 150, 151 vibrate due to fluid flow through theflow tube 100 of the flow sensor 210. Vibration of the first and secondpiezo elements 150, 151 creates an ultrasonic signal which can bedetected and communicated electronically to the microprocessor. Themicroprocessor is configured to correlate the ultrasonic signal to afluid flow rate through the flow tube 100 and provide a fluid flow rateoutput to the user.

Method of Readying a Flow Sensor

Referring to FIGS. 1-2, use of a flow sensor system 200 of the presentdisclosure will now be described. In one example, as the drug isinjected, the flow sensor system 200 measures the volume dosedultrasonically. In order to improve transmission of ultrasonic signalsin the flow sensor 210, the present disclosure proposes various examplesof increasing a fluid pressure in the flow sensor 210.

During manufacture, flow sensor 210 may be calibrated on a calibrationbench. For example, a fluid, such as water, is flowed through the flowsensor 210 to calibrate the ultrasonic signal transmission between thefirst and second piezo elements 150 and 151. Prior to packaging the flowsensor 210 for shipping, the flow sensor 210 may be dried, such as usinghot air, to eliminate any residual fluid that may remain in the flowsensor 210. Without intending to be bound by theory, hot air drying ofthe fluid path surfaces of the flow sensor 210 contributes to makingthese fluid path surfaces exhibit their inherently hydrophobiccharacteristics. In this manner, when the flow sensor 210 is readied foruse by priming the flow sensor 210 with a priming fluid, the interiorfluid path surface of the flow sensor 210 may not be fully wetted withthe priming fluid. Because the flow sensor 210 is configured to generateultrasonic signals corresponding to a flow rate of the fluid throughcontact with the internal flow path of the flow sensor 210, theinherently hydrophobic characteristics of the interior surface of thefluid path contribute to a decrease in the ability of the flow sensor210 to transmit ultrasonic waves. It has been found that wetting theinternal surfaces of the flow path through the flow sensor 210, such asby increasing a pressure or maintaining a pressure within the flow path,increases the ultrasonic signal transmission capability of the flowsensor 210.

With reference to FIG. 1, a first method of readying the flow sensor 210will now be described. In this example, the flow sensor system 200 isprepared for use by attaching the injection port 130 of the flow sensorsystem 200 to an administrable fluid source, such as a syringe 900containing a fluid. In some examples, the syringe 900 may contain apriming fluid, such as saline. Prior to connecting the syringe 900, theinjection port 130 is desirably cleaned by swabbing the hub according tonormal hospital procedure. The syringe 900 can be attached to theinjection port 130 by rotating the syringe 900 about its longitudinalaxis until the syringe 900 stops, i.e., a secure connection between thesyringe 900 and the injection port 130 is made. The syringe 900 has aplunger 920 for delivering the priming fluid from an interior of thesyringe 900 when the plunger 920 is pushed in a distal direction.

In some examples, a flow director 999 can be attached between theinjection port 130 and the syringe 900. The flow director creates aspiral fluid flow in the fluid delivered from the syringe 900 to theflow path in the fluid sensor 210, which can increase an amount ofmicro-bubbles dislodged from the inner walls of the flow path of thefluid sensor 210 and/or increase absorption of the micro-bubbles in thefluid.

The outlet connection 105 is capped with a flow restrictor, such as acap 910. In some examples, the cap 910 is configured to interface withthe Luer tip 109 of the outlet connection 105. The cap 910 can beattached to the Luer tip 109 by rotating the cap 910 about itslongitudinal axis until the cap 910 stops, i.e., a secure connectionbetween the cap 910 and the Luer tip 109 is made. Once connected to theLuer tip 109, the cap 910 blocks fluid flow from the outlet connection105.

In some examples, a negative pressure can be applied to the fluid in anadministrable fluid source, e.g., the syringe 900, before delivering thefluid from the syringe 900 to the flow path of the flow sensor, therebydegassing the fluid in the syringe 900. For example, a vacuum device 996as shown in FIG. 3, such as a manual elastomeric suction cup, can beattached to the injection port 130 of the flow sensor 210 beforeattaching the injection port 130 of the flow sensor system 200 to anadministrable fluid source, e.g., before delivering fluid into and/orthrough the flow sensor 210. The vacuum device 996 can be actuated toapply the negative pressure to the fluid in the syringe 900, which canreduce the partial pressure of syringe 900 before delivering the fluidfrom the syringe 900 to the fluid sensor 200.

In some examples, one or more surfactants, such as those disclosed inU.S. Patent Nos. 7,264,885 and 7,560,494, which are hereby incorporatedin their entirety by reference, are used to wet the internal surfaces ofthe flow path of the flow sensor 210 before delivering the fluid intoand/or through the flow sensor 210, which can increase contact of thefluid with the internal surfaces of the flow path.

After the syringe 900 is attached to the injection port 130 and theoutlet connection 105 is capped with a flow restrictor, the plunger 920of the syringe 900 is pushed in the distal direction to deliver fluidfrom the syringe 900. Because the cap 910 prevents fluid from flowingout of the outlet connection 105, the priming fluid from the syringe 900builds fluid pressure within the flow sensor 210. In some examples, anincreased fluid pressure of 5-50 psi within the flow sensor 210 can bemaintained for a predetermined period of time. For example, thepredetermined period of time may be approximately 1-60 seconds. In otherexamples, a fluid pressure of greater than 50 psi within the flow sensor210 can be maintained for a predetermined period of time, which may begreater than 60 seconds.

In some examples, a constant pressure can be applied to the fluid in theflow sensor 210 over a period of time. The constant pressure may be aconstant positive pressure or a constant negative pressure. A syringeactuation device, e.g., a bar clamp and spreader, may be attached to thesyringe 900 to apply a constant force to the plunger 920 of the syringe900, which results in the constant pressure being applied to the fluidin the flow sensor 210 capped with the cap 910. For example, the syringeactuation device can be adjusted to a first position in which thesyringe actuation device applies the constant force to the plunger ofthe syringe.

In another example, a bi-directional flow of the fluid can be created inthe in the flow path of the flow sensor 210. A first constant pressurecan be applied to the fluid in the flow sensor 210 over a first periodof time, and a second constant pressure can be applied to the fluid inthe flow sensor 210 over a second period of time that is one of beforethe first period of time and after the first period of time. The firstconstant pressure may be a positive or negative constant pressure, andthe second constant pressure is the other of the positive or negativeconstant pressure. A syringe actuation device, e.g., a bar clamp andspreader, may be attached to the syringe 900 and adjusted to a firstposition in which the syringe actuation device applies a first constantforce to the plunger 920 of the syringe 900, thereby applying the firstconstant pressure to the fluid in the flow sensor 210 over the firstperiod of time. The syringe actuation device 944 can be adjusted to asecond position in which the syringe actuation device 944 a secondconstant force to the plunger 920 of the syringe 900, thereby applyingthe second constant pressure to the fluid in the flow sensor 210 overthe second period of time. For example, the syringe actuation device maybe adjusted to a position that depresses the plunger 920 of the syringe900 to deliver the fluid into and/or through the flow sensor 210 andapply a positive pressure thereto. The syringe actuation device canmaintain the syringe in the depressed position for a desired orpredetermined period of time. The syringe actuation device may beadjusted after the first period of time to a position that pulls theplunger 920 of the syringe in an opposite direction of the directionthat depresses the plunger to apply a negative pressure to the fluid inthe flow sensor 210, thereby creating a flow of the fluid from theoutlet connection 105 toward the injection port 130. The syringeactuation device can maintain the syringe in the pulled-back positionfor a desired or predetermined period of time. The syringe actuationdevice can be alternated between the positions to create a chaoticbi-directional flow of the fluid in the flow sensor 210.

In some examples, a pressure sensor can be connected between the syringe900 and the injection port 130. The pressure sensor can be configured tomeasure a pressure in the fluid flow sensor 210 and provide an output ofthe measured pressure to a user. The user can adjust the syringeactuation device based on the measured pressure to achieve a desiredpressure in the flow sensor 210. In another example, the pressure sensorcan communicate with the controller 930 or another computing deviceconfigured to automatically control an electromechanical syringeactuation device based on the measured pressure to achieve the desiredpressure in the flow sensor 210.

As discussed herein, the syringe actuation device may comprise a clamp,such as a bar clamp and spreader, that can be adjusted between positionsthat maintain the plunger 920 in various depressed and/or pulled-backpositions. In another example, the syringe actuation device may comprisea piston or rod configured to engage the plunger 920 of the syringe 900in a manner that enables the piston to depress the plunger 920 distallywhen advanced and pull-back the plunger 920 proximally when retracted.The piston or rod may be driven by a rotational mechanism, such asincluded in the force limiting device 1010 described herein with respectto FIG. 8, a latching mechanism, such as included in a spring biasedgrip drive or a ratchet driven grip drive, e.g., as used in well-knowncaulking guns, and/or as described herein with respect to the forcelimiting device 1030 described with respect to FIG. 9, or a linear forcemechanism that applies a direct linear force to the piston, such as aloaded spring or a ratcheting mechanism as described herein with respectto the force limiting device 1050 described with respect to FIG. 10. Inother words, the force limiting devices 1010, 1030, and 1050 describedherein with respect to FIGS. 8, 9, and 10, respectively, each include asyringe actuation device according to non-limiting embodiments oraspects of the present invention.

Regardless of a type of syringe actuation device used to apply a forceto the plunger, it is contemplated that the syringe actuation device canbe configured to be manually driven and controlled or configured to beautomatically driven and controlled by a computing device, such as thecontroller 930, based on input from at least one sensor, such as thepressure sensor, a flow rate sensor, a volume sensor, a timer, or anycombination thereof. For example, the controller 930 or anothercomputing device may compare a current pressure of the fluid in thefluid sensor determined by the pressure sensor to a desired pressure andcontrol an operation of the syringe actuation device to adjust theplunger to achieve the desired pressured based on the current pressure.

In another example, with respect to FIG. 7, the syringe 900 can bemounted vertically in a syringe holder 990. The syringe holder 990 maycomprise an opening 991 configured to receive the syringe 900. Flangesof the syringe 900 may on laterally extending surfaces 992 of thesyringe holder 990. The distal end of the syringe 900 extends throughthe opening 991 and is accessible for connection to the injection port130 of the fluid sensor 210. A load 992 can be applied to the plunger920 of the syringe 900 while the syringe 900 is held in the verticalorientation by the syringe holder 990. The load 992 applies a constantforce or pressure to the plunger 920, thereby resulting in a constantpressure being applied to the fluid in the flow sensor 210 over a periodof time that the load is applied.

While the flow sensor 210 is pressurized by the fluid from the syringe900, at least one first signal is generated by the flow sensor 210 tocharacterize at least one attribute of fluid. In various examples, theat least one attribute may be fluid flow rate and/or fluid pressure. Themanual increase of fluid pressure within the flow sensor 210, whilekeeping the outlet connection 105 capped, helps eliminate any airbetween the interior surface of the flow path of the flow sensor 210 andthe fluid. In this manner, the interior surface of the flow path of theflow sensor 210 is fully wetted to allow for an increased ultrasonicsignal transmission of the flow sensor 210.

Next, the pressure on the plunger 920 of the syringe 900 can bereleased, and the cap 910 is removed from the Luer tip 109. The outletconnection 105 is attached to an inlet of a fluid pathway (not shown)configured for delivering fluid from an administrable fluid source, suchas the syringe 900, to a patient. In some examples, the fluid pathwaymay be a catheter configured for connecting to a patient. Prior toconnecting the fluid pathway to the patient, fluid from the syringe 900is first expelled from the fluid pathway, such as during the priming ofthe fluid pathway. As the fluid is delivered from the syringe 900, thefluid flows through the flow sensor 210 and out of the fluid pathway. Insome examples, 2-7 ml of fluid may be delivered from the syringe 900through the fluid pathway. The flow sensor 210 may generate at least onesecond signal of the same type as the first signal in order tocharacterize at least one attribute of the fluid. For example, thesecond signal may characterize the pressure and/or flow rate of fluidthrough the flow sensor 210. In some examples, the second signal may beincreased (i.e., have higher strength) than the first signal due to theinternal surfaces of the flow path of the flow sensor 210 being fullywetted. For example, the second signal may be increased over the firstsignal by 120%, 160%, or 180%, inclusive of the values therebetween. Theflow sensor 210 is now primed and ready for use in a fluid deliveryprocedure.

In some examples, the flow sensor 210 can be shook or vibrated when thefluid is within the fluid channel, thereby dislodging micro-bubbles fromthe inner walls of the flow sensor 210. The dislodged micro-bubbles canbe removed from the flow sensor 210 by flushing the fluid from the flowsensor 210. In one example, the flow sensor 210 can be manually shook orvibrated. In another example, as shown in FIG. 2, a vibrator 997 can beattached to the flow sensor 210 or directly to the flow tube subassembly 10 to shake or vibrate the flow sensor 210. In another example,the first piezo element or the upstream transducer 150 and/or the secondpiezo element or the downstream transducer 151 can be activated to applyan ultrasonic transmission to the flow sensor 210 to dislodgemicro-bubbles from the inner walls of the flow path of the flow sensor210. The first and second piezo elements 150, 151 can be activatedbefore or without taking a measurement therewith. As the fluid isdelivered from the syringe 900 after vibrating the flow sensor 210 oractivating the first and second piezo elements 150, 151, the fluid flowsthrough the flow sensor 210 and out of the fluid pathway, carryingdislodged micro-bubbles out of the flow sensor 210.

In another example, the fluid within the flow sensor 210 can be heated,which can expand a gas carrying capacity of the fluid prior to flushingthe fluid out of the flow sensor 210. For example, a heating element998, such as a variable resistor heating element, can be attached to theflow tube sub assembly 10 or another element of the flow sensor 210 andapply heat to the flow tube sub assembly 10 including the fluid in thefluid sensor 210 before the fluid is flushed from the fluid sensor 210.By increasing the gas carrying capacity of the fluid, more micro-bubblescan be carried by the fluid out of the flow sensor 210 when the fluid isflushed from the flow sensor 210.

In various examples, the flow sensor 210 may be in communication with acontroller 930. The controller 930 may be configured for receivinginformation from the flow sensor 210, such as receiving the at least onefirst signal and the at least one second signal. The controller 930 maybe configured to determine that the at least one attribute of the fluidbased on the received data from the at least one first signal and the atleast one second signal matches at least one condition specified by atleast one rule. For example, the controller 930 may be configured foridentifying a type of fluid flowing through the flow sensor 210 based ona flow rate of the fluid through the flow sensor 210 for a given fluidpressure at a given fluid temperature. Without intended to be bound bytheory, each fluid, such as a fluid medicament, has a unique ultrasonicsignature as the fluid flows through the flow sensor 210. The ultrasonicsignature may be a function of fluid pressure, temperature, and materialcomposition of the fluid.

In various examples, the controller 930 may generate at least oneoperation modification signal in response to the characterized at leastone attribute matching at least one condition specified by at least onerule. For example, the controller 930 can execute a flow algorithm basedon data representing characteristics or attributes of the fluid flowreceived from the piezo elements 150, 151. In some examples, the syringe900 may have indicia that, when read by a reading device of the flowsensor system 200 that is in operative communication with the controller930, causes the controller 930 to initiate a predetermined operatingcycle. In some examples, the indicia may be a 2D or 3D barcode, QR code,or any other indicia capable of storing information that, when read by areading device of the flow sensor system 200, is configured to beinterpreted as a set of instructions to be performed by the controller930. For example, the indicia, when read by the reading device, cancause the controller 930 to initiate a priming cycle for priming theflow sensor 210. In some examples, the priming cycle may comprisegenerating at least one signal, such as a first signal and a secondsignal discussed herein.

The controller 930 may transmit, by a transmitter (not shown) theoperation modification signal to at least one device. In someembodiments, if a fluid type is determined to be a different type than adesired fluid type, or if a flow rate is determined to be a differentflow rate than a desired flow rate, the controller 930 can transmit anoperation modification signal to a display and/or a data processingmodule that causes the module to display an alarm or alert or causes themodule to transmit a signal back to the system 200 that stops the fluidflow. The controller 930 can further control the wireless transmitter totransmit injection data representing a type of medication, a dose of amedication, and/or a time of a dose of a medication to the displayand/or data processing module. In some embodiments, the controller 930can automatically transmit the data to the module in response to anautomated injection.

With reference to FIG. 5, a graph depicting a percentage of signalstrength of five flow sensors 210 as a function of time is shown inaccordance with one example. Each flow sensor 210 was initiallycalibrated using a standard calibration routine. The signal readingsfrom each of the flow sensors 210 after calibration are shown as point Aon the graph. The flow sensors 210 were then dried with hot air andflushed with a priming fluid without being pressurized. Ultrasonicsignal transmission readings were then recorded, shown as point B on thegraph. From the graph in FIG. 5, it can be readily observed that signalstrength drops for each of the flow sensors 210 after the flow sensors210 have been dried with hot air. In order to increase the signal level,each flow sensor 210 was capped with a cap 910 and pressurized with apriming fluid, such as saline, for 60 seconds. After the expiration ofthe pressurization period, another signal reading was taken. Point C inFIG. 5 illustrates that the signal level increases from Point B afterthe flow sensors 210 have been pressurized with a priming fluid.

With reference to FIG. 2, instead of capping the outlet connection 105with a cap 910, such as described herein with reference to FIG. 1, theoutlet connection 105 may be connected to a vented flow restrictor, suchas a vented cap 940. The vented cap 940 comprises an orifice or outlet942 that provides a fluid flow path from the outlet connection 105through the vented cap 940 to atmosphere. In some examples, the ventedcap 940 may be a needle having an inner diameter sufficiently small tobe capable of generating back pressure in the flow sensor 210 when fluidis delivered from the syringe 900. For example, the vented cap 940 maybe a needle having an outlet of approximately 30 G (0.16 mm innerdiameter (ID)). In other examples, the vented cap 940 may have an innerdiameter of 0.1-0.2 mm. In another example, the vented cap 940 maycomprise a smaller orifice or outlet 942, for example an outlet of lessthan 30 G (0.16 mm ID), for example, an outlet of approximately 34 G(0.0826 mm ID) or less. The priming fluid delivered from the syringe 900builds back pressure within the flow sensor 210. In some examples, anincreased fluid pressure of 5-50 psi or greater within the flow sensor210 can be maintained for a predetermined period of time. For example,the predetermined period of time may be approximately 1-60 seconds.

In another example, a varying pressure can be applied to the fluid inthe flow sensor 210. The vented cap 940 can be configured to change aninner diameter of the orifice or outlet 942 of the vented cap 940 as afunction of the fluid pressure within the fluid sensor 210. For example,the vented cap 940 can comprise an elastomeric material having anelasticity that enables the outlet 942 to deform in response to appliedpressure. When a pressure within the flow sensor 210 is sufficient toovercome the elasticity of the outlet 942 of the vented cap 940, forexample, in response to a build-up of pressure within the flow sensor210 from the delivery of the priming fluid, the outlet 942 of the ventedcap 940 deforms in response to the increased pressure to increase theinner diameter. The increase in the inner diameter of the outlet 942 ofthe vented cap 940 enables a higher rate of fluid flow from the ventedcap 940, which can reduce the back pressure in the flow sensor 210. Whenthe back pressure in the fluid sensor 210 is no longer sufficient toovercome the elasticity of the outlet 942 of the vented cap 940, theinner diameter of the outlet 942 of the vented cap 940 returns to itsoriginal or resting diameter. If the priming fluid is continued to bedelivered, the back pressure in the flow sensor 210 may begin increasingagain until the pressure is again sufficient to overcome the elasticityof the outlet 942. The inner diameter of the outlet 942 of the ventedcap 940 can thus be changed over time to create a perturbative fluidflow within the fluid sensor 210 during priming, which can improvewetting of the interior surface of the flow path of the flow sensor 210to allow for an increased ultrasonic signal transmission of the flowsensor 210.

In some examples, a flow rate of the fluid delivered from theadministrable fluid source to the fluid channel through the fluid inletcan be varied. For example, the delivering the fluid from the syringe900 to the fluid sensor 210 may comprise delivering boluses of the fluidto the flow path of the fluid sensor 210. The boluses may beperiodically delivered to the fluid channel at standard or variable timeintervals. The boluses may be varied from one another by at least oneof: a volume of the boluses, a pressure applied to the fluid of theboluses within the flow sensor 210, a period of time over which thepressure is applied to the fluid of the boluses within the flow sensor210, or any combination thereof. In one implementation, anelectromechanical device can be configured to automatically deliver theboluses to the fluid sensor at the periodic time intervals.

In some examples, a force limiting device 1010, 1030, or 1050, such asdescribed herein with respect to FIGS. 8, 9, and 10, respectively, canbe attached to the syringe 900. The force limiting device 1010, 1030, or1050 may include a syringe actuation device as described. The forcelimiting device 1010 or 1030 may inhibit an application of a pressure tothe fluid in the fluid channel of the fluid sensor 210 that violates athreshold pressure. For example, the force limiting device 1010 or 1030may inhibit movement of the plunger 920 of the syringe 900 (or a syringeactuation device thereof driving the plunger 920) in response to theapplication of the pressure to the fluid in the fluid channel of thefluid sensor 210 that violates the threshold pressure. In anotherexample, the force limiting device 1050 may include at least onepressure indicator that indicates a current pressure applied to thefluid in the fluid channel.

While the flow sensor 210 is pressurized by the fluid from the syringe900, at least one first signal is generated by the flow sensor 210 tocharacterize at least one attribute of fluid. In various examples, theat least one attribute may be fluid flow rate and/or fluid pressure. Themanual increase of fluid pressure within the flow sensor 210, whilekeeping the outlet connection 105 capped, helps eliminate any airbetween the interior surface of the flow path of the flow sensor 210 andthe fluid. In this manner, the interior surface of the flow path of theflow sensor 210 is fully wetted to allow for an increased ultrasonicsignal transmission of the flow sensor 210.

Next, the pressure on the plunger 920 of the syringe 900 can bereleased, and the vented cap 940 is removed from the Luer tip 109. Theoutlet connection 105 is attached to an inlet of a fluid pathway (notshown) configured for delivering fluid from an administrable fluidsource, such as the syringe 900, to a patient. In some examples, thefluid pathway may be a catheter configured for connecting to a patient.Prior to connecting the fluid pathway to the patient, fluid from thesyringe 900 is first expelled from the fluid pathway, such as during thepriming of the fluid pathway. As the fluid is delivered from the syringe900, the fluid flows through the flow sensor 210 and out of the fluidpathway. In some examples, 2-7 ml of fluid may be delivered from thesyringe 900 through the fluid pathway. The flow sensor 210 may generateat least one second signal of the same type as the first signal in orderto characterize at least one attribute of the fluid. For example, thesecond signal may characterize the pressure and/or flow rate of fluidthrough the flow sensor 210. In some examples, the second signal may beincreased (i.e., have higher strength) than the first signal due to theinternal surfaces of the flow path of the flow sensor 210 being fullywetted. For example, the second signal may be increased over the firstsignal by 120%, 160%, or 180%, inclusive of the values therebetween. Theflow sensor 210 is now primed and ready for use in a fluid deliveryprocedure.

With reference to FIG. 6, a graph depicting signal level of three flowsensors 210 (labeled 1, 2, 3) as a function of time is shown inaccordance with another example. Each flow sensor 210 was provided witha vented cap 940 having a 30 G needle. A signal count was recorded(Point D) during a delivery of 2 ml of fluid from the syringe 900. Thevented cap 940 was then removed from each flow sensor 210 and a signalcount illustrative of a pressure drop was recorded (Point E). From thegraph in FIG. 6, it can be readily observed that signal strength dropsfor each of the flow sensors 210 after the vented cap 940 is removedfrom the flow sensors 210. After removing the vented cap 940, 7 ml offluid was delivered from the syringe 900 through each flow sensor 210.During this step, signal count increased and stabilized at a high value(Point F). A signal level of a fourth flow sensor 210 (labeled 4 in FIG.6), which has been primed without using the vented cap 940, is shown asa comparative example. The signal strength of the fourth flow sensor 210is significantly lower than a signal strength of flow sensors 210 thatwere readied using the vented cap 940 in a manner described herein withreference to FIG. 2.

Force Limiting Device for Readying a Flow Sensor

FIGS. 8-10 illustrate exemplary configurations of a force limitingdevice of a flow sensor system of the present disclosure. Referring toFIG. 8, a force limiting device 1010 for controlling the plunger 920 ofthe syringe 900 to deliver a fluid from an interior of the syringe 900comprises an actuator rod 1012 extending from a proximal end to a distalend. A plunger engagement portion 1014 is engaged with the distal end ofthe actuator rod 1012 and configured to engage the plunger 920 of thesyringe 900. For example, an outer wall at the distal end of the plungerengagement portion 1014 can engage the plunger 920. A clutch 1020engages the distal end of the actuator rod 1012 to the plungerengagement portion 1014. A spring 1018 extends within the actuator rod1012.

The force limiting device 1010 further comprises a body 1016 having aproximal end, a distal end, and an opening at the proximal end. Theopening receives the plunger engagement portion 1014. The plungerengagement portion 1014 is threadably engaged with the body 1016. Forexample, an inner wall of the body 1016 can comprise male threading orfemale threading, and an outer wall of the plunger engagement portion1014 can comprise the other of the male threading or the femalethreading. In one example, the threading is multi-start high leadthread. The distal end of the body 1016 is configured to connect to thesyringe 900, e.g., to a flange on the body of the syringe, and theplunger 920 of the syringe 900 extends within the body 1016 when thesyringe 900 is connected to the body 1016. The body 1016, when connectedto the syringe 900, prevents axial movement of a body the syringe 900with respect to the body 1016, while allowing for axial movement of theplunger 920 within the body 1016. In some examples, the body 1016 may beformed of a first half and a second half that can be placed togetheraround the syringe and connected via a snap-fit connection to connectthe body 1016 to the syringe 900.

The spring 1018 extends within the actuator rod 1012 and into theplunger engagement portion 1014 via an opening in a proximal end of theplunger engagement portion 1014. The spring 1018 engages an inner wallat the distal end of the plunger engagement portion 1014. The actuatorrod 1012 extends into the plunger engagement portion 1014. A portion ofthe actuator rod 1012 that extends within the plunger engagement portion1014 includes a radially extending flange 1013. The clutch 1020 connectsa proximal face of the radially extending flange 1013 to the inner wallat the proximal end of the plunger engagement portion 1014.

The clutch 1020 is configured to disengage the distal end of theactuator rod 1012 from the plunger engagement section 1014 in responseto a compression of the spring 1018. For example, a spring constant ofthe spring 1018 may determine a force required to disengage the clutch1020. The spring 1018 compresses in response to a plunger reaction forceapplied by the plunger 920 of the syringe to the plunger engagementportion 1014. The compression of the spring 1018 enables the actuatorrod 1012 to move distally with respect to the plunger engagement portion1014, such that the proximal face of the radially extending flange 1013disengages and separates in the distal direction from the inner wall atthe proximal end of the plunger engagement portion 1014, therebydisengaging the clutch 1020. For example, the plunger reaction forceapplied to the plunger engagement portion 1014 by the plunger 920 istransferred to the spring 1018, which compresses the spring 1018.

The plunger engagement portion 1014 is configured to inhibit anapplication of a force to the plunger 920 of the syringe 900 thatviolates a threshold force. For example, the plunger engagement 1014 canportion inhibit movement of the plunger 920 of the syringe 900 inresponse to a plunger reaction force applied by the plunger 920 of thesyringe to an outer wall at the distal end of the plunger engagementportion 1014. With the clutch 1020 engaged, a rotational force appliedto the actuator rod 1012 is transferred to the plunger engagementportion 1014, which rotates in the threaded engagement with the body1016 to move the plunger engagement portion 1014 axially with respect tothe body 1016. With the clutch 1020 disengaged, a rotational forceapplied to the actuator rod 1012 is not transferred to the plungerengagement portion 1014, thereby inhibiting further axial movement ofthe plunger engagement portion 1014 with respect to the body 1016 and anapplication of a force to the plunger 920 of the syringe 900 thatviolates a threshold force set by the spring 1018.

Referring to FIG. 9, a force limiting device 1030 for controlling theplunger 920 of the syringe 900 to deliver a fluid from an interior ofthe syringe 900 comprises a handle 1032 and a cooperating trigger 1034,which may be connected by a first joint 1035. The trigger 1034 comprisesa first portion 1034 a connected to a second portion 1034 b by a secondjoint 1036. A spring 1038 further connects the first portion 1034 a tothe second portion 1034 b.

The handle 1032 and the cooperating trigger 1034 can be configured tooperate a latching mechanism, such as included in a spring biased gripdrive or a ratchet driven grip drive, e.g., as used in well-knowncaulking guns. The first portion 1034 a of the trigger 1034 isconfigured to transfer a driving force to the plunger 920 of the syringe900. The first portion 1034 a may be configured to directly engage theplunger 920, or engage the plunger 920 via at least one of a drive gripor plate 1040 and piston 1042, the details and operation of which arewell-known to those of skill in the art and, thus, omitted in theinterest of brevity. Although not shown in the interest of clarity inthe drawings, the force limiting device 1030 may comprise a bodyextending from the handle 1032 configured to hold the syringe 900stationary with respect the handle 1032 during operation of the plunger920 by the force limiting device 1030. Such configurations for holding afluid container during fluid delivery are well-known to those of skillin the art, examples of which can be found in U.S. Pat. Nos. 4,299,336and 6,155,463, hereby incorporated by reference in their entirety.

Movement of the trigger 1034 toward the handle 1032 may apply astretching force to the spring 1038. For example, as the first portion1034 a engages and applies the driving force to the drive plate 1040, aplunger reaction force is applied by the plunger 920 to the firstportion 1034 a of the trigger 1034 in a direction opposite to thedriving force, which may partially or completely inhibit movement of thefirst portion 1034 a with the second portion 1034 a, therebytransferring the movement of the second portion 1034 b to the spring1018 as the stretching force. The first portion 1034 a of the trigger1034 disengages the plunger 920 or drive plate 1040 in response to astretching force greater than a threshold force applied to the spring1038. For example, a spring constant of the spring 1038 may determine aforce required to disengage the first portion 1034 a from the plunger920 or drive plate 1040 such that the first portion 1034 a cannotprovide the driving force in the direction opposite the plunger reactionforce.

In response to a plunger reaction force applied by the plunger 920 thethe first portion 1034 a that is greater than the threshold force, thestretching force applied to the spring 1038 due to the movement of thetrigger 1034 toward the handle 1032 exceeds the spring constant of thespring 1018, thereby stretching the spring and increasing a distancebetween the first portion 1034 a and the second portion 1034 b until thefirst portion 1038 is forced to disengage from the plunger 920 or thedrive plate 1040. For example, the first portion 1034 a may breakawayand invert its position with respect to the joint 1036 as shown in FIG.9, thereby preventing any further application of force to the plunger920 via the force limiting device 1030.

Referring to FIG. 8, a force limiting device 1050 for controlling theplunger 920 of the syringe 900 to deliver a fluid from an interior ofthe syringe 900 comprises an actuator rod 1052 extending from a proximalend to a distal end. A spring 1054 extends within the actuator rod 1052.A distal end of the spring 1054 is configured to engage the plunger 920of the syringe 900.

The force limiting device 1050 further comprises a body 1056 having aproximal end, a distal end, and an opening at the proximal end, whereinthe opening receives the distal end of the actuator rod 1052, andwherein the actuator rod 1052 comprises at least one indicator 1058 thatindicates a desired amount of compression of the spring 1054. The distalend of the body 1056 is configured to connect to the syringe, theplunger 920 of the syringe 900 can extend within the body 1056.

In some examples, an outer wall of the actuator rod 1052 may be inratcheting engagement with an inner wall of the body 1056. For example,a distal end of the actuator rod 1052 may include a radially extendingpawl, and the inner wall of the body 1056 may include a plurality ofteeth.

At least a portion of the actuator rod 1052 and at least a portion ofthe body 1056 may be transparent such that the spring 1054 and theplunger 920 are visible through the actuator rod 1052 and the body 1056.A location of the at least one indicator 1058 with respect to a locationof at least one of a distal end of the spring 1058 and a proximal end ofthe plunger 920 can indicate the desired amount of compression of thespring 1058, for example, for during a priming operation as describedherein.

In some examples, the actuator rod 1052 may include at least twoindicators spaced apart from one another. A location of the at least oneof the distal end of the spring 1058 and the proximal end of the plunger920 between the at least two indicators can indicate the desired amountof compression of the spring 1058.

Method of Using the Flow Sensor System

To use a primed flow sensor system 200, a user attaches the flow sensor210 to the base 220 by joining the flow sensor 210 (tubing side) andbase 220 front sections first, and then snapping the two together.Preferably, an audible snapping sound is heard to indicate a secureconnection between the flow sensor 210 and the base 220. In one example,connecting the flow sensor 210 to the base 220 automatically powers onthe flow sensor system 200. In one example, the connection of the flowsensor 210 to the base 220 is verified by a blinking light on the base220. In other examples, other indicators may be used.

The flow sensor system 200 is now ready for delivery of IV medications.In one example, in the event of a flow sensor system 200 failure(excluding the IV fluid pathway), the flow sensor system 200 will stillallow standard medication or fluid delivery through the port.

Next, giving an injection using the flow sensor system 200 will bediscussed. First, the injection port 130 is cleaned by swabbing the hubaccording to normal hospital procedure. Next, a syringe 900 can beattached to the injection port 130 of the flow sensor 210 by completelyrotating the syringe 900 until the syringe 900 stops, i.e., a secureconnection between the syringe 800 and the injection port 130 is made.Ideally, the caregiver double checks each medication name andconcentration on the syringe 900 prior to attachment to the injectionport 130 to assure the correct medication is given.

The flow sensor 210 can be disposed after the flow sensor 210 is used tosense the flow of at least one fluidic medicament. The flow sensor base220 can be used with a plurality of different flow sensors 210.

While this disclosure has been described as having exemplary designs,the present disclosure can be further modified within the spirit andscope of this disclosure. This application is therefore intended tocover any variations, uses, or adaptations of the disclosure using itsgeneral principles. Further, this application is intended to cover suchdepartures from the present disclosure as they become within known orcustomary practice in the art to which this disclosure pertains andwhich fall within the limits of the appended claims.

What is claimed is:
 1. A system comprising: a fluid sensor including: afluid channel, a fluid inlet at a first end of the fluid channelconfigured to couple to an outlet of an administrable fluid source, anda fluid outlet at a second end of the fluid channel; and a flowrestrictor configured to be attached to the fluid outlet of the fluidsensor.
 2. The system of claim 1, wherein the flow restrictor comprisesan outlet having an inner diameter that changes in response to a varyingpressure applied to a fluid in the fluid channel, thereby creating aperturbative flow of the fluid in the fluid channel.
 3. The system ofclaim 2, wherein the flow restrictor comprises an elastomeric material.4. The system of claim 1, wherein the flow restrictor includes an outletof approximately 34 G.
 5. The system of claim 1, wherein theadministrable fluid source includes a syringe including a plunger, andwherein the system further comprises: a syringe actuation deviceconfigured to apply a force to the plunger of the syringe, which resultsin a pressure being applied to a fluid in the fluid channel.
 6. Thesystem of claim 5, further comprising: a pressure sensor configured todetermine a current pressure of the fluid in the fluid channel; and acontroller programmed and/or configured to: communicate with thepressure sensor; and control, based on the current pressure, the syringeactuation device to adjust the force applied to the plunger of thesyringe to achieve a desired pressure of the fluid in the fluid channel.7. The system of claim 6, wherein the controller is programmed and/orconfigured to: control the syringe actuation device to apply a firstconstant force to the plunger of the syringe that applies a constantnegative pressure to the fluid in the fluid channel over a first periodof time; and control the syringe actuation device to apply a secondconstant force to the plunger of the syringe that applies a constantpositive pressure to the fluid in the fluid channel over a second periodof time that is one of before the first period of time and after thefirst period of time.
 8. The system of claim 5, wherein the syringeactuation device includes a force limiting device configured to inhibitan application of the pressure to the fluid in the fluid channel thatviolates a threshold pressure.
 9. The system of claim 8, wherein theforce limiting device includes: an actuator rod extending from aproximal end to a distal end; a plunger engagement portion engaged withthe distal end of the actuator rod and configured to engage the plungerof the syringe; and a body having a proximal end, a distal end, and anopening at the proximal end, wherein the opening receives the plungerengagement portion, and wherein the plunger engagement portion isthreadably engaged with the body.
 10. The system of claim 8, wherein theforce limiting device includes: a handle and a cooperating trigger,wherein the trigger comprises a first portion connected to a secondportion by a joint; and a spring connecting the first portion to thesecond portion, wherein the first portion of the trigger is configuredto engage the plunger of the syringe and receive a plunger reactionforce applied by the plunger of the syringe, wherein movement of thesecond portion of the trigger toward the handle applies a stretchingforce to the spring in response to the plunger reaction force, andwherein the first portion of the trigger disengages the plunger of thesyringe in response to the stretching force greater than a thresholdforce applied to the spring.
 11. The system of claim 8, wherein theforce limiting device includes: an actuator rod extending from aproximal end to a distal end; a spring extending within the actuatorrod, wherein a distal end of the spring is configured to engage theplunger of the syringe; and a body having a proximal end, a distal end,and an opening at the proximal end, wherein the opening receives thedistal end of the actuator rod, and wherein the actuator rod comprisesat least one indicator that indicates a desired amount of compression ofthe spring.
 12. The system of claim 1, wherein the administrable fluidsource includes a syringe including a plunger, the system furthercomprising: a syringe holder configured to vertically mount the syringe;and a load configured to be applied to the plunger of the syringe whenthe syringe is vertically mounted in the syringe holder.